1. Field of the Invention
The present invention relates to a method of analyzing a subject for Attention Deficit Hyperactivity Disorder (ADHD), more particularly to a quick (short duration), quantitative method of ADHD analysis, and to a system and device for performing the analysis. The present invention additionally relates to a method, which can be used to quantitatively measure the treatment endpoints for the subject, i.e., appropriate levels of stimulants.
2. Technical Background
Attention Deficit Hyperactivity Disorder (ADHD) is a disorder that inhibits an individual's capacity to regulate activity level, inhibit behavior, and attend to tasks. ADHD is the most common developmental disorder of childhood, affecting 5-15% of school age children, or approximately 2 million children in the United States. ADHD may interfere with the ability to learn or to develop satisfactory interpersonal relationships and may result in academic failure, inability to fulfill intellectual potential, poor self-esteem, or socially maladaptive behavior. In general, when ADHD is left untreated there is a gradual accumulation of adverse processes and events that increase the risk of serious psychopathology later in life.
The current ADHD diagnosis in children is subjective and varies according to the method and opinions of the specialist. Generally it involves interviewing the children, parents, teachers, and school staff, etc. The specialist will then incorporate and analyze all of the data obtained and make a decision based on his/her findings.
To overcome the problems associated with the current subjective assessment methods, a variety of objective methods of assessing the symptoms of ADHD have been devised. These tests tend to assess the level of attention, the level of activity, and the impulsivity control in an objective manner. One of the more common objective methods for studying sustained attention is the test of variation of attention (TOVA) during which the subject is asked to select stimulating signals out of a series of sequential auditory or visual signals. ADHD subjects miss stimuli more frequently (omission errors) or more often have commission errors, defined as erroneous responses to insignificant stimuli. Also, the reaction time of ADHD patients is prolonged.
Using a neurological assessment approach, a number of studies have focused on differentiating ADHD from normal subjects based on brainwave measures such as the EEG power spectrum. Since ADHD is considered a result of a CNS dysfunction, and the EEG directly measures the brain activity, it has the potential to be an appropriate tool for assessing ADHD. In particular, a recent paper by Robert Barry and their colleagues contain a comprehensive review of the previous work along with their recent findings with regards to the promising potential of EEG for detection of ADHD. These studies generally show that children with ADHD produce excess brainwaves in the lower frequency bands (e.g, theta frequency, 4-8 Hz) compared to the higher frequency bands such as alpha (8-12 Hz) and beta (15-35 Hz). For example, Ucles and Lorente's study analyzed EEG during eyes-closed resting condition (similar to the test protocol of this study) and reported that theta/alpha ratio from occipital leads can discriminate ADHD from normal children.
An object of the present invention is to introduce an objective, practical, and quantitative means of assessing ADHD by combining a portable multi-channel wireless EEG acquisition and analysis device with a quick (15-minute) auditory-based test of maintenance of attention. The system is developed for the identification and quantitative evaluation of children with ADHD and for gauging the effectiveness of medication on neurobehavioral indices and parameters.